Depositional age and provenance of metasedimentary rocks from the Hengshan Complex, North China Craton: Implications for the late Neoarchean to early Paleoproterozoic tectonic setting of the Trans-North China Orogen

The Late Neoarchean to Early Paleoproterozoic Zhujiafang supracrustal assemblage is comprised of banded iron formations (BIF) interlayered with amphibolites, schist, felsic gneisses, and quartzite, intruded by mafic dykes and granitic intrusions or veins. Whole-rock geochemical and Nd isotopic and zircon U–Pb-Hf isotopic studies were conducted on the metasedimentary rocks from the Hengshan Complex, Trans-North China Orogen, North China Craton, to constrain their depositional age, provenance, and tectonic setting, and identify the impact of source weathering and sedimentary processes. Geochemical data classify these metasedimentary rocks as immature greywackes, showing weak- to intermediate-source weathering, poor sorting, and negligible sedimentary recycling. Relative to average Archean Cratonic Shales, the average major oxides of the Hengshan metasedimentary rocks have almost identical characteristics. The Chondrite-normalized rare earth element (REE) plots for these metasedimentary rocks show fractionated REE patterns ((La/Yb)N = 4.93–31.45), alongside moderate negative to slightly positive Eu anomalies (δEu = 0.68–1.17). Whole-rock Nd isotopic data give positive εNd(t) values ranging from + 0.34 to + 2.78. The zircons of two samples yield detrital zircon age range of ca. 2.59–2.48 Ga, with superchondrite εHf(t) values (+2.25 to + 6.08), and have experienced late modification. These findings suggest that the sediments originated from a blend of felsic and mafic sources, predominated by Late Neoarchean to Early Paleoproterozoic granitoids and metavolcanic rocks from the Huai'an, Hengshan, and Wutai complexes, excluding the TTG gneisses from the Fuping Complex. The Nd isotopic signatures, coupled with values of Th/U, δEu, Th/Sc, and other element characteristics, point to a Young Undifferentiated Arc provenance. The detrital zircon age spectrum, complemented by Hf isotope analysis, further delineates the depositional environment as a continental island arc setting, with a maximum depositional age of ca. 2.48 Ga.